Fig. 4
A human organ-on-a-chip microphysiological system integrated with sequential NP-guided detection systems. a A cross-sectional view of a human gut-on-a-chip where complex interactions of gut microbiome, epithelium, and immune components occur. Reproduced with permission [21]. Copyright 2016, Elsevier. b “Detection unit 1” for the on-line monitoring of cellular and microbial secretomes in the gold nanorod-deposited microfluidic channel. Reproduced with permission [86]. Copyright 2015, American Chemical Society. c “Detection unit 2” sequentially connected to the “Detection unit 1” to validate the differentiation of neural stem cells mimicking the physiological interaction of gut-brain axis using graphene oxide-encapsulated gold NP-guided electrochemical detection. Reproduced with permission [88]. Copyright 2013, Elsevier